The duration of untreated illness in major depressive disorder: Clinical relevance, predictors, and strategies for early intervention

The time elapsed between the initial onset of depressive symptoms and the beginning of appropriate treatment is a key determinant of clinical outcomes in affected individuals. A prolonged delay in initiating care is associated with great symptom severity, reduced response to treatment, increased risk for chronicity, cognitive impairment, and higher rates of suicidal behavior. The present narrative review explores the main factors contributing to treatment delays, their impact on illness progression, and the strategies available to promote early intervention. Through a structured search of the scientific literature, studies were grouped into three thematic domains: predictors of treatment delay, clinical consequences, and approaches to reduce delays. Results highlight the central role of attitudinal barriers, such as stigma, poor awareness of symptoms, and fear of psychiatric medications as major contributors to postponed help-seeking, often more robust than structural or economic limitations. Socio-demographic and clinical features, such as early age of onset or recurrent episodes, are also associated with longer delays. Neuroimaging and cognitive research suggest that untreated depressive symptoms may lead to persistent changes in brain function and structure. Reducing the time to treatment by means of early detection systems, community-based programs, and integrated models of care could be essential to improve recovery, prevent chronicity, and reduce the overall burden of depressive illness. • Longer DUI in MDD may be linked to greater symptom severity and suicidality • Stigma and low mental health literacy often emerge as key attitudinal barriers • Early onset, recurrent episodes, and bipolar depression appear associated with prolonged DUI • Some studies suggest a link between DUI and cognitive or neural alterations • Integrated early intervention models are proposed to reduce treatment delays